


Get His Goat

by frick



Category: Undertale (Video Game)
Genre: Adult Asriel Dreemurr, Adult Frisk, Blow Jobs, Dom/sub, M/M, Penises, Porn, Precum, Rain Sex, Teasing, Tongues, Transformation, cum, dicks stuck in boxers, drool, pre
Language: English
Status: Completed
Published: 2016-06-04
Updated: 2016-06-04
Packaged: 2018-07-12 04:41:08
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 4,395
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/7085962
Author URL: https://archiveofourown.org/users/frick/pseuds/frick
Summary: <blockquote class="userstuff">
              <p>Frisk has been out of town for a few days and Asriel wants to light up the bedroom with hot meme magic.</p><p>Read the tags, I'm not responsible for unwanted boners.</p>
            </blockquote>





	Get His Goat

**Author's Note:**

> Edited by the wonderful Motif
> 
> Also encouraged by. Possibly bullied. Definitely was bullied into writing this.

Rain. The torrent of water beating against the roof of the house had a certain soothing quality that Asriel couldn’t quite put his finger on. He was lying in bed, thumb swiping against the harsh white of a phone screen, its light contrasting with the muted grey of the afternoon light and the pitter patter gently caressing his ears. 

Asriel tapped the lock button as Frisk’s silhouette darkened the orange light from the bathroom, slipping it under the covers against his chest. 

“What, now you’re hiding something from me?” The human carried a tone of bored indifference that matched his default expression eerily. Asriel should have been able to easily brush it off.

He would have, if he didn’t actually have something to hide. “N-no, just looking at some stuff before bed.” Asriel shifted his arms behind his head in an attempt to play it off. “If I just had the rain to keep me entertained while you used up all the hot water, I’d have passed out half an hour ago.”

Frisk leaned back and turned the bathroom light off, before slowly approaching the bed. “Where’s my phone, then, Az?”

Shit. At least he’d had the foresight to clear all of the open tabs before stowing it. “Mine’s dead. Thought it’d be okay if I used yours.”

“Mhm. ‘Thought it’d be okay’, which is why you’re blushing like a guilty child and hid the phone under the blanket. C’mon, hand it over.”

Asriel complied, withdrawing the phone from the covers and offering it to Frisk, carefully avoiding eye contact by staring blankly at the powered-off television across the bedroom. His mind raced with a barrage of viable excuses for what he was actually doing with the device.

The truth was, he had been digging through Frisk’s porn collection for ideas. They’ve had a... Bit of a dry spell, since Frisk had been away on a trip. Asriel had an almost limitless library of lewd magics, but he lacked the imagination and confidence to exercise them in the bedroom without some kind of prompting, or failing that, copious amounts of alcohol. Once Frisk was in the right state of mind, he was like putty in Asriel’s hands… But getting him there often took a combination of foresight and bravado that Asriel sometimes struggled with.

“The apps are all cleared. What were you doing?”

Asriel coughed, stalling for time. The best lies were mostly true, so... “I mmmmmight have been looking at porn. Y-you know, trying to get in the mood.” 

Frisk lowered the phone and held up an inquisitive eyebrow. “You hate looking at human porn.”

“Yeah, well, we haven’t done anything in a bit, and I’m-”

The human leaned forward on the bed, kicking off his jeans and grinning lewdly. “It has been a while, huh? I was actually just thinkin’ about it.”

Thankfully, he bought it. Asriel fidgeted as Frisk pulled the comforter off of him, Asriel’s manhood rapidly expanding against Frisk’s questing, groping hand. Not the ideal circumstances for turning vague ideas into action, honestly. 

It was hard to concentrate, what with Frisk determinedly smearing the inside of his boxers with pre while he ran the other hand through the soft fur on Asriel’s thigh, creeping his fingers ever closer to the- Focus, Dreemurr.

It was time to come up with a plan.

**

Frisk licked his lips as he marveled at the bobbing, glistening cock, entranced by the way it bounced as he peeled Asriel’s boxers down. His own erection begged for attention as it pressed against his briefs. Frisk moved to press the advantage, a hungering flame alight in his eyes, ready to-

“A-ah! Frisk, not so fast! You’ve been gone for so long, can’t we enjoy a little, uh, foreplay, or something?”

The human blinked. “Foreplay. We’re both sitting here leaking on this perfectly nice bed and you want... Foreplay.” Frisk felt a tingling in his groin but he chose to ignore it in lieu of being a smartass. “Should I go put on some Buddy Rich while I’m at it?”

Wait. Frisk noticed Asriel’s visage darken slightly as a grin spread across the boss monster’s maw. 

Shit. He was doing some kind of magic nonsense.

The sight of black tendrils winding across Asriel’s fur like shadows always unsettled Frisk, although Frisk couldn’t tell if it was because it was creepy, or the pavlovian association caused by the perverse lewdness that invariably followed in its wake. The caprine blinked and white, glowing irises stared back at Frisk through the amber fog of the dim lamp. The last of the afternoon light had bled into darkness, along with Frisk’s chances of having a normal evening.

“No need for music, Frisk. You’ll be singing my favourite song soon enough.”

Frisk gulped. “C-come again?”

“In time. I’ll be honest, it wasn’t regular human porn I was browsing on your phone. I’m surprised, Frisk. I mean, you’ve always been such a slut for my paws, but, well, being given your own? Wasn’t expecting that.”

Crap. He found the fuckin’ private folders. 

“Delta rune to unlock ‘em. Cute, honestly.”

And now he was reading minds again, fucking fantastic. 

Asriel chuckled, and Frisk felt an absence of a pressure he hadn’t noticed until it was gone, as Asriel pulled his magic away. “You needn’t worry, Frisk. Why would I bother reading your mind, when you were so kind as to sort your desires into folders by kink. Almost like you wanted to be found out.”

The same river of magic slipped into Frisk’s chest, causing Frisk’s snappy retort to die in his throat, too shocked to resist as the force dug down to his loins and weaved into Frisk with a rhythm that felt akin to a heartbeat. Frisk strained mentally to resist the urge to fondle himself in front of Asriel as the sensation gushed against his cock, which strained against his briefs, unconcerned as to what manner of embarrassing torment lay in store for it so long as it also involved pleasure.

“Honestly, Frisk, I’m surprised you didn’t come to me sooner. This should have been offered willingly! I’m not just your master, I’m your partner too. The first person to tell. ”

“Y-guh, damnit-You know I’d be a lot more forthcoming about this sort of shit if you weren’t always so fuckin’ smug about it!” Frisk pulled himself back onto his knees, shifting his hips so his member wasn’t so painfully visible to Asriel. “Not to mention that snooping around my private files is a gross invasion of privacy!”

“You know, I’d almost buy that you’re upset about this if you weren’t harder than a rock and leaking like a tap.”

Frisk cursed his traitorous biology, nervously glancing at his throbbing erection. The heartbeat was pulsing between his legs, feeling halfway between a massage and a cramp. There was no sign of fur, yet. 

“Don’t worry, you won’t miss any of the action. According to what I saw, you like to watch.”

Frisk couldn’t tell if the blushing was from the magical stimulation assaulting them from the inside, or Asriel’s lurid teasing. “Just… Just shut up. You of all people shouldn’t be so excited about this weirdness.”

“What, I’m supposed to not like transformation because I was trapped in a flower? How do you think kinks happen in the first place, Frisk? You’re a lot like me, in some ways.” Asriel pulled himself off of his back and leant close to Frisk’s face, letting out the faintest hint of a lewd growl under his breath as he ran a thumb down Frisk’s cheek. “Hell, after tonight... You’ll be like me in another way.”

Christ, this was happening. The peculiar magical pulse moved within Frisk, right on cue, causing Frisk to wince as it kinda tickled and kinda itched its way down his legs, causing him to shift uneasily and prop himself back on his elbows, grimacing at his now tingling feet.

Unfortunately, this put him in a prime position for Asriel’s teasing. The boss monster clasped a hand around Frisk’s right ankle and pulled his leg straight, manipulating Frisk’s toes and sending experimental jolts of magic through the balls of his feet.

“Now, this shouldn’t hurt, but you might feel a little uncomfortable to start. I mean, physically uncomfortable, as opposed to your cute little show of temptation and resistance. I’ll go slow to start with. Whimper with pleasure if you want me to speed up.”

God, his sing song tone of voice was intolerable. Frisk’s member ached against his shorts. “Can we j-just… Get on with it? So we can take care of this?” He tried to gesture towards his loins and locked up, gasping as he felt his foot crack. He reflexively pushed himself backwards, his shoulders meeting resistance against a magical barrier Asriel must have erected. He really didn’t want Frisk to miss the sights.

The human dug his hands into the blankets at his sides as he watched Asriel manipulate his form like putty, looking pensive for a moment before pushing Frisk’s toes together and sculpting them into a familiar monstrous shape. The urge to wiggle his toes was intense enough to make Frisk’s leg shake as he watched Asriel carefully pull a claw out of his big toe, white fur beginning to bristle out of the skin with each movement. 

The same tingling sensation was spreading across Frisk’s other foot, but the angle and blankets prevented him from getting a proper look. Asriel gestured for Frisk to shift his leg sideways, so he could tilt the human’s knee. Frisk complied, shifting on the bed and trying not to stare at the underside of his foot, utterly failing as he noticed the beginnings of what were unmistakably pawpads pushing their way out of the fine white fur that was slowly spreading across Frisk’s foot. 

Asriel glanced up from his work, his smile curling into a lewd grin as he caught Frisk staring. “You can touch it, you know. I heard that little moan of yours, there’s no point in pretending you don’t want this.”

Frisk bit his lip, hesitating for a moment before curiosity and desire won out against shame. He reached forward, fingers brushing against the blooming fur that had made its way up to his ankle. He held his hand still for a moment, entranced at the sensation of the new fur pushing against his fingertips as it grew out, plus the unmistakable sensation of the bones under the flesh shifting and changing to account for the new toe arrangement. Right on cue, Frisk felt the skin hardening along the bottom of his foot, the fur parting to allow black paw pads to surface. Frisk poked at one of them gently and marveled at the tough but still soft texture. All the while, the sensation of Asriel’s magical influence continued to creep up his legs. 

Okay. You’ve got goat feet now. Asriel just gave you goat feet.

A couple of experimental twitches and flexes confirmed that Frisk did indeed have boss monster paws. The fur creeping up his legs seemed to have slowed down for now, giving Frisk some time to adjust. Frisk experimentally shifted the paw around and brought his other leg out of the cocoon of blankets to stare at them.

It took a couple of attempts to clear his throat enough to speak. “I-is it done?”

Asriel rested his head on one hand, looking smug. “You tell me. I mean, there’s a lot of human left.”

Despite the changes being complete, Frisk could still feel residual magic buzzing through his phalanges. He bit back the urge to beg for more and lose himself in the moment. The loss of stimulation in his, well, paws, had bought another desire to Frisk’s attention. . 

“C-can we… I mean, like-” Frisk gestured wordlessly down at his pre-stained, tented underwear.

Asriel raised an amused eyebrow and leaned forward again. He pushed a commanding finger against Frisk’s shame, causing Frisk to jump. “You want this taken care of first, huh?”

Yes. Please, yes. Frisk nodded enthusiastically, blushing and mute with embarrassment, but also, an erection.

“Or... We can take care of both at the same time.”

Frisk clenched the sheets under him. He was almost frightened by how much the suggestion turned him on, and painfully aware that Asriel had his finger pressed against Frisk’s erection, which had throbbed with arousal, right on cue.

Asriel purred appreciatively, having elicited the desired response. “I mean, I did go through your phone. That seemed to be a common theme.” 

Asriel dragged Frisk’s shorts down, exposing the pre-drenched shaft to the chilly air of the bedroom, causing Frisk to squirm in discomfort. Asriel lowered his head and stuck out the tip of his tongue, dragging it along the underside of Frisk’s manhood, the caprine’s saliva sending waves of frost down Frisk’s spine.

The human leaned back on one arm and used the other to grip against one of Asriel’s horns, letting out desperate pants that became faster and more urgent as the tingling sensation of magic began slowly traveling up his legs once more, the white fur resuming its march upwards. The sensation of newly grown fur rubbing against Asriel’s long ears felt alien, strange, not to mention the way the sheets felt against Frisk’s new paws as he curled his paw pads and claws against the bed. The barrage of lewd and unusual sensations bypassed all of Frisk’s inhibitions and filters, and he was moaning and squirming on the bed as though it was his first time as Asriel took Frisk’s member into his maw proper.

Asriel started bobbing his head up and down against Frisk’s thighs, his tongue massaging the quivering member, pre gushing out with every movement. Frisk watched himself shift under the combined assault of magic and pleasure. The magic had crept its way into his groin, tingling his orbs and reinforcing the pulses of arousal that increased in fervor as Frisk watched his pubic hairs flush out into white tufts of fur.

Frisk realised what was about to happen, mortified at the airless whimper of desire that escaped his lips. 

The caprine lapped under Frisk’s balls, his long tongue easily capable of massaging the entirety of Frisk’s cock with length to spare. Frisk could feel Asriel’s smug grin, the reflexive swallow, the press of warm, slick flesh against his length, the tingling of magic making its way across his balls and creeping its way to his tip. Frisk tightened his grip against Asriel’s horns, throwing his head back and letting out a startled gasp as he came, Frisk incapable of distinguishing between the orgasm and the magic as waves of pleasure rolled across his body, his grip too weak to stop Asriel from pulling away after a couple of spurts, his cock sending the rest of the surprisingly numerous strands of cum across his chest and Asriel’s snout. 

Frisk collapsed against the sheets and panted, feeling like he just run a marathon. He shuddered at the sensation of Asriel’s cum-and-pre tainted saliva stringing down from the boss monster’s maw onto his legs and still present erection.

That definitely just happened. Frisk attempted to sit up, and flustered themselves again as their hand brushed against a furry thigh.

His own furry thigh. Frisk gulped and redoubled his efforts. Asriel was nestled in between Frisk’s legs, chin resting in his hands as he stared with possibly the most smug grin he’d ever had. 

Frisk noticed some blemishes across his legs. They looked strangely familia-

“I did say ‘like me’, didn’t I?”

“You fuckin’ narcissist! Hyperdeath tattoos?”

“Mhm. Awfully sassy for someone who was whimpering like a virgin a few seconds ago. And you still haven’t noticed the best part yet!”

The best part? Frisk was monster from the waist down, and had just busted one of the bigger nuts of his entire life at the exact moment of change, what could possibly be the ‘best part’ about being covered in his own… 

Huh. Things were awfully dry in the chest and stomach department, considering how recently Frisk had painted there. He hesitated to look down, eyes locked by Asriel’s haughty gaze. 

He eventually mustered the strength, looking down at a suspiciously arranged grouping of fur patches across his belly. They looked all the world like splatter marks.

“...Really!?”

The boss monster gave out an amused snort of air. “Gotta hand it to whoever makes your porn. They’re inventive! Now hold still.” 

Asriel pulled himself up to Frisk’s waist, resting his ass dangerously close to Frisk’s spent but still eager cock. Frisk noticed the fur spreading slowly outward from under Asriel’s fur, causing another unintentional twitch of his length. He looked at Asriel’s own manhood, which was drooling.

“We’ll take care of that later. I can hardly leave you half done, can I?” Asriel slipped an index finger into his maw and slathered it in saliva, drawing it free and rubbing the finger and his thumb together as if testing for consistency. He then leaned over and started drawing shapes across Frisk’s chest, symmetrically on both sides, almost as if...

Frisk looked down at the black fur sprouting through the glistening residue left behind by the first of Asriel’s light touches. “This was definitely not in my porn folder.”

Asriel gave a shrug and continued on his arts and crafts, drawing circles down Frisk’s arms and humming to himself. The wet spots started to vanish just like Frisk’s load had, being replaced by strips and shapes of void-black fur. The white fur from Frisk’s chest continued to spread, covering uncovered skin and thickening out into a crested puff near his sternum.

After making the final mark, the boss monster raised back up, arms crossed with yet another smug grin. Frisk squirmed as the last of the fur covered his neck and fingers. From the chin down he was now a boss monster. No, even worse, he was perfectly Asriel’s double. 

“If I could trust you to not immediately drop the spaghetti, I’d leave it on for a few days. Give myself some time off while you fumble about in royal meetings.”

Frisk thought of a retort that was quickly quelled as Asriel lifted himself off of Frisk and teetered off of the bed. Asriel casually strolled over to the foot of it and stared at Frisk expectantly.

What was he-

“You got to have your fun. Where’s mine?”

Unbelievable. “You’re not even gonna fucking finish the job?” Frisk rubbed a furred hand against the line of skin and fur under his chin.

“Well, I could leave you like that. Send you out to… I don’t know, get milk or something? Try to pass as human for the entire trip. Wouldn’t that be fun?”

Frisk contemplated Loading; he had saved before the flight home. 

“Oh, don’t be like that. I gave you the rest of the body for free. I’ll trade head for head.” The smile across the boss monster’s lips threatened to split Asriel’s head in two.

Oh, you’re real fuckin’ clever. 

“Mhm. And you probably can’t Load with your body like that anyway. So…”

Frisk was gonna do it. There wasn’t a single part of him that was truly struggling against it. And he knew Asriel; he’d gladly leave his body in this state to prove a point. 

Goddamnit.

Frisk lifted himself up and half rolled, half pushed himself to the end of the bed, mentally preparing himself for what he was about to do.

“Golly, it’s just a blowjob, Frisk. You’ve done it before.”

The magic thrumming in his body intensified as he got closer to Asriel’s salivating erection, accentuating his heartbeat as his brain slowly realized what was about to come out of this. The sensation of his new fur rubbing against the sheets and bedding on the mattress sent fresh waves of ice down his back.

Asriel always found ways to surprise Frisk. This would be a night to remember. 

Frisk swung his legs around the end of the bedframe and attempted to stand up, dealing with the uneasy footing his new paws were dealing with. 

“Well?”

Fuck. Frisk lowered himself onto his knees, mouth level with Asriel’s length. He shot another look up, and noticed the boss monster’s smug facade was breaking, blush piercing through his cheeks and eyebrows lacking their taunting edge. The ex-human gulped to clear his throat. Might as well make it quick and get it over with.

At least Frisk could take pleasure in turning the tables on Asriel.

Frisk wrapped his lips around Asriel’s tip, shivering slightly as the taste of his pre started causing his mouth to tingle. He tried to ignore it and push on, his jaw taking in Asriel’s length, internally smirking to himself as Asriel let out a half moan, half bleat, Frisk manipulating his tongue against Asriel’s underside.

The tongue acrobatics ceases as Frisk noticed his mouth… Swelling? Asriel’s tip was pressed into the roof of his mouth, the underside pushed against his tongue, and he couldn’t risk taking any more without pressing against it with teeth. This was odd. Frisk could generally take more than this. 

Asriel’s lewd murmurs turned to giggles. Frisk pulled his head free and let out a panicked stammer as his tongue lolled out of his mouth, brushing against his chin and almost landing against his chest. The tingling was intensifying, with an oily sheen coating the entirety of Frisk’s organ.

Frisk tried to bring the tongue back in, succeeding in only a couple of inches before giving up. He lifted his head and stared at Asriel incredulously. The pringling in his mouth continued in waves with the rest of the magic that beat through his body. 

Asriel cocked his head and grabbed Frisk roughly by the chin, and Frisk hesitated again, wondering if this was a legitimate mistake or if Asriel was fucking with him again.

“Lemme fix that tongue issue for you.” Asriel plunged both of his thumbs roughly into Frisk’s mouth, gripping against his teeth, and wrapped his fingers around his cheeks. Frisk noticed the sensation in his mouth started to permeate the entirety of his skull.

The world seemed to stretch as Asriel suddenly and violently tugged. The sight of his face being pulled out like a cartoon made Frisk let out a panicked bleat, the tan mass in the bottom of his vision rapidly growing pale white, along with the hair brushing the top of his eyes. He experimentally drew his tongue back into his mouth and shut his jaw, making sure everything was in order. Asriel withdrew his thumbs and pushed them against the bridge of Frisk’s nose… Snout, whatever. The room shifted again as Frisk’s eyes parted slightly, and Frisk blinked away tears as some of the virulent saliva dipped into his eyes.

Asriel shoved a hand into Frisk’s hair and grabbed onto… something, Frisk couldn’t tell what, sight still blurry as needles pierced through his vision. He felt a sick pulling against his cranium and saw how Asriel shifted his grasp and mused that it must have been horns.

He had horns. Fucking hell. Asriel interrupted the thought, pulling Frisk’s newly-grown maw against his tip. Frisk parted his jaw and accepted, letting his fresh tongue and much larger mouth wash over the length of Asriel, feeling him already beginning to twitch. As Frisk began sliding his head down Asriel, he noticed two white puffs moving about in the peripheral of his vision, barely aware enough to register that they were his ears. The prince gave out a series of shallow pants as Frisk pressed the advantage, taking in enough of Asriel to graze his new nostrils against Asriel’s crotch fur, finally feeling as if he had gained some of his self respect back as he melted away Asriel’s smugness with every moan and almost-bleat. 

Frisk felt Asriel buck his hips and pulled his head back, narrowly escaping boss monster spunk slathering against his new fangs. Asriel let out a loud, lewd groan as a spurt of cum landed on the top of Frisk’s snout, the rest coming out in fresh puddles over the hardwood floor. 

The couple stayed in their spots for a minute, collection themselves after… whatever had just happened. Asriel made the first motion, wiping the seed off of Frisk’s face and dragging it across his cheeks.

Aww. Face tattoos. How cute and also disgusting. 

To go along with the thought, Asriel conjured up a phantasmal mirror, presenting it to Frisk. 

Asriel stared back at him through the mirror. It took a few funny faces and quick glances at the actual Asriel for it to click that Frisk really was a doppelganger.

“You know, you were right. Maybe making you exactly like me is a little narcissistic.”

“A little?” Jesus, he even had the same voice. “I know I tell you to fuck yourself a lot, Az, but this is a tad over the top.”

“Any ideas? Just changing the tattoos isn’t enough. I could glamour your eyes shut, turn you brown… put a collar on you, heh.” 

Uh oh. 

“In fact, now that I think about it, I did see some shipping confirmation in your email about a choker… have you been hiding something else from me, Frisk?”

Don’t think about the box under the bed, don’t think about the-

“Box under the bed, huh? How’s the collar look? Subtle, have a clasp, or…”

This mindreading shit was getting to be too much. “Leather. No tag or anything.”

“Aaaaand?”

Fuck. “Black.”

“Perfect!” Asriel hooked a thumb into his mouth, wetting it, and slid it across Frisk’s throat with an agonizing slowness. Almost immediately, a band of black fur pushed through the white along his neck. Frisk tried to hook an index finger into it, hoping it was an illusion, or that he could remove it, but his finger just dug into fur. 

“This isn’t a collar. This is a fuckin’ branding.”

“Well, if you could take it off it wouldn’t be much good, would it?”

“I’m going to shave off your fur when you sleep tonight.”

Asriel ignored the threat and walked over to pick up his boxers. “You cleared up the weekend, right? No obligations for a few days?”

Frisk sighed in defeat. “Not a thing.”

“Great! I’ll keep you like this for a bit, then. Always wanted a twin.”


End file.
